Analysis of mechanisms and frequency of CDKN2A/B gene loss during progression of RAS-transformed rat embryo fibroblast clones.

Zhou, J N; Hashemi, J; Helou, K; Zhang, A; Röhme, D; Zetterberg, A; Levan, G; Linder, S

Zhou, J N; Hashemi, J; Helou, K; Zhang, A; Röhme, D; Zetterberg, A; Levan, G; Linder, S.

Afiliación

Zhou JN; Radiumhemmet's Research Laboratory, Karolinska Institute and Hospital, Stockholm, Sweden.

Somat Cell Mol Genet ; 24(6): 327-39, 1998 Nov.

Article en En | MEDLINE | ID: mdl-10763411

RESUMEN

Rat embryo fibroblasts (REFs) are inefficiently transformed by RAS-oncogenes. Induction of p16INK4A expression by RAS has been suggested to contribute to this resistance. Glucocorticoid hormones, (DEX), enhance REF transformation by RAS and facilitates the isolation of transformed and immortal cell lines. We show that DEX induced cell proliferation is paralleled by a decrease in Cdkn2a gene transcripts, suggesting a mechanism for hormone promotion. The mechanisms of progression into hormone independent cell lines were examined. Twenty-two of 30 clones which reached a population size of approximately 10(6) cells could be established as cell lines. All lines studied showed homozygous deletions of the Cdkn2 loci (Cdkn2a and Cdkn2b) on RNO5. LOH was found for all RNO5 genetic markers examined in 7 of 19 cell lines, suggesting non-disjunction events. In the remaining 12 cell lines, both copies of Cdkn2 appeared to be lost by deletions/rearrangements, some of which could by demonstrated by karyotype analysis. We conclude that (i) clonal expansion of RAS-transfected REF by DEX is paralleled by down-regulation of Cdkn2a expression; (ii) homozygous deletion of Cdkn2 were estimated to occur at a frequency of 2 x 10(-8)/cell/generation or higher, and (iii) deletion/rearrangements and nondisjunction appear to be the main mechanisms leading to deletion of Cdkn2.

Asunto(s)

Proteínas Portadoras/genética; Proteínas de Ciclo Celular; Transformación Celular Neoplásica/genética; Inhibidor p16 de la Quinasa Dependiente de Ciclina/genética; Fibroblastos/metabolismo; Eliminación de Gen; Genes ras/genética; Proteínas Supresoras de Tumor; Animales; Proteínas Portadoras/metabolismo; Línea Celular Transformada; Células Clonales; Inhibidor p15 de las Quinasas Dependientes de la Ciclina; Regulación hacia Abajo/genética; Embrión de Mamíferos; Fibroblastos/patología; Homocigoto; Humanos; Cariotipificación; Pérdida de Heterocigocidad/genética; Ratas; Ratas Endogámicas BN; Ratas Endogámicas Lew

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Colección: 01-internacional Base de datos: MEDLINE Asunto principal: Proteínas Portadoras / Transformación Celular Neoplásica / Genes ras / Eliminación de Gen / Proteínas de Ciclo Celular / Inhibidor p16 de la Quinasa Dependiente de Ciclina / Proteínas Supresoras de Tumor / Fibroblastos Límite: Animals / Humans Idioma: En Revista: Somat Cell Mol Genet Año: 1998 Tipo del documento: Article País de afiliación: Suecia Pais de publicación: Estados Unidos

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